High tension circuit breakers



Jan. 3, 1956 H. FORWALD HIGH TENSION CIRCUIT BREAKERS Filed March 17, 1953 2 Sheets-Sheet 1 /l'\ WA 1 0r Haakon fbrwa/d Jan. 3, 1956 H. FORWALD 2,729,721

HIGH TENSION CIRCUIT BREAKERS Filed March 17, 1953 2 Sheets-Sheet 2 r5 rq I 4 5 f4 :1 4

/r\ Vl'l for" Ha a kon Forwa 7d United States Patent 015cc HIGH TENSION cnzcurr BREAKERS Haakon Forwald, Ludvika, Sweden, assignor to Alhnanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application March 17, 1953, Serial No. 342,890 Claims priority, application Sweden March 19, 1952 Claims. (Cl. 200-145) In modern high tension circuit breakers generally a voltage dependent resistance is coupled in parallel with the breaking gaps. In the case that the circuit breaker contains a plurality of breaking gaps each gap is provided with a separate parallel resistance. This device, however, is combined with a serious disadvantage in that if one of the gaps should reignite, the resistance in parallel with it will be short-circuited by the arc and consequently the remaining resistances in the chain will be over-loaded.

According to the present invention this disadvantage is avoided thereby that in a circuit breaker having a plurality of breaking elements the whole series of breaking gaps is connected in parallel with a series of voltage dependent resistances which are connected with the breaking gaps only at the ends of the series.

In the case that the circuit breaker is provided with an ordinary disconnecting switch, the residual current flowing through the resistance is interrupted by said disconnecting switch. In circuit breakers without any external disconnecting switch the different extinguishing chambers are provided with separate switches interrupting the chain of voltage dependent resistances. In this case the resistances may be arranged in leading through insulators attached to the wall of the extinguishing chamber or compressed air container. It is also possible to arrange the resistances inside the air container or in insulators arranged outside the different air containers.

Fig. 1 shows schematically the connection of the resistances, whereas Fig. 2 schematically shows a circuit breaker having two air containers arranged on separate insulators, each container having two insulating bushings carrying the main breaking gaps and a pair of insulating bushings containing the voltage dependent resistances. In Fig. 3 a circuit breaker is shown having a pair of insulating bushings carrying the main breaking gaps, whereas two voltage dependent resistances are arranged across the said main breaking gaps and arranged inside the air container.

In Fig. 1, 1 designates schematically compressed air containers containing main breaking gaps 2 and auxiliary breaking gaps 3. The latter serve to connect the voltage dependent resistances 4 to form a chain connected in parallel with the whole series of breaking gaps 2.

In Fig. 2, 1 designates compressed air containers mounted on pillar insulators 5 which rest upon a base plate 6. In the wall of the containers insulating bushings 7 are inserted which carry operating cylinders 8 for the main breaking gaps 9. 10 is an operating cylinder for auxiliary breaking gaps 11 serving to connect the voltage 2,729,721 Patented Jan. 3, 1956 dependent resistances 4, which are mounted inside insulating bushings 12 inserted in the wall of the container 1. 13 is an outlet valve for the escape of air from the compressed air container, said valve being operated simultaneously with the bridge 14 of the auxiliary breaking gaps 11. The contacts in the main breaking gaps are provided with a boring, so that the air from the container 1 escapes through said boring out through the outlet valve 13. This boring is, however, not shown on the drawing. The resistances 4 in the dilferent bushings are joined with each other by conductors 15 to form a chain connected with the chain of main breaking gaps in the points 16 and 17, the chain of the breaking gaps being connected by conductors 18.

In Fig. 3 a circuit breaker main breakings gaps 9 carried by insulating bushings 7 inserted in the wall of the container 1. In this device the voltage dependent resistances 4, however, are carried by the insulating bushings 7 and are connected with each other by the bridge 14 of the auxiliary breaking gaps 11. The bridge 14 is, as in Fig. 2, operated by the operating cylinder 10 and the main breaking gaps are operated by the operating cylinders 8. As in Fig. 2, the outlet valve 13 is also operated by the operating cylinder 10, and the whole container 1 is carried by the insulator pillar 5 mounted on the base plate 6.

I claim as my invention:

1. An air blast circuit breaker comprising a compressed air container, a plurality of breaking gaps connected in series and enclosed within said container, insulating means serving to support said container, a series of voltage-dependent resistances connected in parallel with only the extreme ends of the series-connected breaking gaps, and auxiliary breaking gaps connected in series with the said resistances and located within the said container.

2. An air blast circuit breaker comprising a plurality of compressed air containers, breaking gaps located in each container and connected with each other in series, insulating means supporting each of said containers, a series of voltage-dependent resistances connected in parallel with only the extreme ends of the series-connected breaking gaps, and auxiliary breaking gaps connected in series with the said resistances and located within said containers.

3. An air blast circuit breaker according to claim 1, comprising insulating bushings inserted in the walls of said container and carrying the stationary contacts of the auxiliary breaking gaps, the said resistances being inserted in said bushings.

4. An air blast circuit breaker according to claim 1, comprising insulating bushings mounted in the walls of the air container and carrying the stationary contacts of the auxiliary breaking gaps, the said resistances being arranged at least partly outside the air container and within the insulating bushings.

5. An air blast circuit breaker according to claim 1,

in which the said resistances are arranged inside the air container.

is shown having only two References Cited in the file of this patent UNITED STATES PATENTS 2,153,400 

